The First Example of a Monomeric Alumatrane

The novel five-coordinate aluminum adduct Me2HN·AlL (2) [wherein
L = tris(2-oxy-3,5-dimethylbenzyl)amine] containing three six-membered rings has been characterized by spectroscopic and by
X-ray means. This adduct of an alumatrane is the first structurally
characterized monomeric alumatrane derivative, and unlike its
parent alumatrane [Al(OCH2CH2)3N]x, 2 is monomeric in the gas,
solution, and solid states. The X-ray molecular structure of 2 reveals
a tricyclic cage moiety of C3 symmetry. The aluminum geometry
is a slightly distorted trigonal bipyramid in which, quite unexpectedly,
the metal atom is located somewhat below the plane formed by
three equatorial oxygens and its Al−Ntertiary bond is shorter than
that in Me3N·AlH3·NMe3 (Heitsch, C. W.; Nordman, C. E.; Parry,
R. W. Inorg. Chem. 1963, 2, 508).